Sunday, July 26, 2009

Fitting the Nut

Sunday, July 26, 2009

Not having parts and then having to make yet another unanticipated business trip have really slowed down progress this week, but I have been able to get a little bit done.

As you might recall, one of the last things I did last week was to seal my test soundboard with a mildly diluted hide glue formula. After it dried for a couple days, I spent about two hours hand-sanding it off to what looks like bare wood. It is my understanding that the goal here is to “clog” the otherwise open pores of the wood with the hide glue to prevent the stain from soaking in too much without inhibiting the stain from getting to the majority of the wood fibers. From what I have read of other people’s attempts at this, its almost impossible to sand it off too much. So, armed with my trusty 80 grit paper followed by some 120 and then 220 grit paper, I sanded off the dry hide-glue layer. Here is what it looks like.

One of the interesting things I found while sanding the glue off was that this is a really good opportunity to find and correct many of the imperfections in the contour of the top. The hide-glue dries just a little bit darker than the color of the raw spruce so each dip and valley, regardless of how shallow, shows up. I was quite surprised at the number of irregularities I found. I believe using this will really help the appearance of the finished mandolin.

With the fretboard now in place, it was time to install the nut. But before I could do that, I realized I needed a padded block to go under the neck while the mandolin is laying on its back to prevent hold the peghead off of the workbench. For this I picked a scrap piece of wood that measured about 1-1/2” x 3” x 4”, cut a shallow wedge in the center of the 4” long face, and glued a piece of soft leather to it. Here is how it looks.

NOW it was time to install the nut.

I started by measuring the width of my slot with my digital calipers. I measured both edges to make sure they were about the same, and much to my surprise, they were within .001” of each other.

I then measured my nut blank (bone - ordered and received way back).

Since the difference between the two was almost half the thickness of the nut blank, I decided to use my drill-press-drum-sander to get it roughly to size. (I used a piece of scrap would to verify the thickness before committing to the nut itself).

Once run through the drum sander, I measured again.

With less than 1/10th of an inch remaining to trim, I stopped there and finished sizing by hand.

I already new that the height of the blank would need to be trimmed but before I could do that, I needed to be able to mark the correct fret height on the nut and this could most easily be done once the nut was correctly sized to fit the slot.

Now to find a way to mark it.

I read somewhere that somebody had taken a wooden pencil, cut it down the center to create a “half” pencil and used this to mark the fret height - so that is what I did. Rather than try to cut the pencil, though, I used my drum sander again to sand away the unwanted half of the pencil.

Using my drum sander once again, I removed all but about 0.30 inches of material above the fret line and then hand-contoured it to shape before gluing it into the slot with Titebond. Here is how it looks now.

As you can see on the top photo above (if you look really hard, anyway) you can see I have marked where the notches for my strings will.

My brother-in-law read my last post where I wrote about buying and using feeler gauges for saws and offered up an old set that he had (and no longer used) for creating my “saws”. Not being one to look a gift horse in the mouth, I accepted and found that this set has a much wider selection of thicknesses.

And, last but not least, the remainder of my parts finally arrived late this week. Now that they are here and assuming I get to stay home a bit more this week, I should be able to get the rest of my binding on and try my hand at staining. I am really looking forward to the staining - if I am lucky, I may get to even try it on the mandolin, not just the test piece.

Thursday, July 16, 2009

Waiting for Parts and Prep to Practice Finishing

Wednesday, July 15, 2009

While it was drying and then after I took the clamps off, it was pretty apparent from the visible gap between the fretboard and neck that I either applied too much hide-glue or that one or both surfaces were not as flat as they should have been. My guess is probably both.

As you can see, the gap on the bass side is significantly more visible than on the treble side. So I faced a choice - leave it and try to fill the gaps or take the fretboard off and try to level and reglue.

I opted for the former.

At this stage, I think I have made more mistakes and bad decisions than not - so I’m OK with filling the gaps and seeing what I can do to make it look good. I am comfortable that this is not one of those items that will make a noticeable difference in the sound or playability, so it should be just fine.

Since I am still waiting for my parts to arrive so I am having to find other little things to work on until the rest of my binding and stain get here. A couple of the things I found I had to do are shaping the nut, trimming the fretboard extension “ears”, and preparing to seal the soundboard for staining.

I have been reading up on different methods for cutting the grooves in the nut for the strings and most of them are kind of expensive. For example, you can spend anywhere from $50 to $100+ for a set of nut files from Stew-Mac or LMI or you can buy similar items on eBay in about the same price range. Another route I read about, though, is a reasonably inexpensive, home-made one that ought to work really well - create some miniature “saws” using feeler gauges. Here is how this works (in theory); each string size has a specific diameter range - in my case the strings will be .011, .014, .025, and .041 inches in diameter. Because the slots in the nut needs to be just a little bit bigger than the string in order to prevent binding, the slots will ideally be cut to just a little bit larger - in my case I am going to target .013, .016, .027, .043. By taking a set of feeler gauges and sawing shallow slots in one edge, with either my bandsaw or a cutting wheel on my Dremel, I can make a range of “saws” that can then be used to cut slots to the appropriate sizes.

So earlier this week, I went to my local auto parts store and bought a set of feeler gauges for right at $6.00.

As you can see, the gauge sizes do not fall exactly on the slot sizes I am looking for, but I read that it is a pretty easy task to wallow a narrow blade enough to get the size slot you need. Of course, one could always using two blades together, too? We’ll see.

Now that the fretboard is glued down and dry I am able trim the extension “ears” down to give the fretboard a more graceful visual transition to the soundboard.

I couldn’t see any easier way to do this than to use my carving tools and then sand them smooth, so that is what I did. Aside from some minor grain issues that made carving a bit tricky, this went pretty smoothly. Here are the finished results.

As you will undoubtedly notice, there is still a fair amount of finish work I need to do to the soundboard scroll, but you can an idea how filling the gaps in the bass side of the fretboard is going to work - obviously a bit more sanding and scraping to do, but I think its looking pretty good.

And finally, I will soon be looking to stain and finish this old girl. But before I do, I thought it a wise idea to try out some of the techniques I have been reading about on my previously ruined soundboards.

Here is the soundboard before sealing it. All that has been done to it (except ruining it, of course) was to sand it down with 320 grit paper.

To begin with, I thought I would try sealing the wood using a slightly diluted mixture of hide-glue.

From what I have read, a lot of people have trouble getting their stains to come out uniform when staining raw wood, especially on the end-grain of spruce soundboards. Consequently, a common practice is to seal the wood first, sand it down really well after it dries, and then apply your stain. As you can imagine, there are many different opinions and options for this, each with its pros and cons, one of which is the hide-glue method. Since I already have it and hide-glue is an accepted sealer by many luthiers, I thought it sounded like a good one for me.

I didn’t find anybody saying exactly what formula they used to mix their glue, only that it needed to be thin enough to brush on, so I went with about a 1 part glue to 3 parts water ratio (by weight) and then heated it up to about 135 degrees F before brushing it on.

If you look closely, you can see in this photo where I have just started brushing the hide-glue on.

And here is what it looks like after 24 hours of drying, but no sanding yet. I will let it cure for another 24 hours before I begin to stand.

Sunday, July 12, 2009

Binding the Soundboard and Installing the Fretboard

Sunday, July 12, 2009

Progress this week was hampered a little bit by a couple things - a short business trip that kept me away for a couple of nights and my most recent order from Stew-Mac is being held with one item on back order. Consequently, about all I was able to accomplish was gluing on some of the binding, attaching the fretboard extension, and gluing on the fretboard.

I finished up last weekend by hand carving the remainder of the grooves for the bindings and then, this week, I shaped and glued the binding around most of the soundboard. Rather than attempting to shape this binding with the heat gun like I did for the fretboard, this time I chose to use a similar to the one I now use to heat my hide glue - hot water. Since the temperature of water does not have to reach boiling to soften the binding, the likelihood of burning oneself and the binding is pretty slim and it is also easier to fine-tune the shape since all you have to do is dip the specific section into the water. I will probably drop the heat gun method now that I know how easy water is to use.

This picture shows the binding being glued on to the outer ring of the scroll. I have used painters tape to hold it and have chosen to glue the scroll first while leaving the body free. This allowed me to focus all my attention on getting the scroll binding tight without having to worry about the body, too. I came back later, after the scroll binding was dry, to glue the remainder of the body binding on.

Next, having run out of binding to glue (I did not order enough to do both the front, back, peghead, and fretboard and the rest is coming in the back-order I mentioned before) I chose to move on to installing the fretboard extension. A couple of weeks ago while waiting for my inlay glue to dry, I spent time making the fretboard extension fit with the soundboard. This meant a good deal of scraping and sanding on the soundboard and the extension itself, but eventually I got the two to fit pretty well. So now, having installed a short strip of binding in between for cosmetics, it was time for gluing

To securely hold the extension while the glue dried, I drilled a hole through it and into the head-block. The screw, being on an angle as it is, creates force both down and back toward the neck. For glue, I used Tite-bond on the base and weld-on cement in the joint that mates with the binding.

After allowing the glue to dry over night, it was time to level the extension with the neck. Checking regularly with a straight edge, I sanded the extension until the two were level.

Finally, I glued the fretboard on. Once again, because it is a relatively normal practice to have to remove or replace a fretboard, I used hot hide-glue for this job. I left approximately a 1/8” gap between the fretboard and the peghead for the nut and I hope to be fine tuning this gap to size and cutting the nut to fit this week.

Friday, July 3, 2009

Inlay and Routing for Binding

Friday, July 03, 2009

Well, as I said on Monday, I have been able to spend quite a bit of time on the mando this week. For starters, I unclamped the body and am really pleased with the way the back came out. Nice and tight and no apparent gaps. Although I said I was planning to use the belt sander to cut down the edges of the top and bottom to match the sides, I chose instead to use my Dremel with a sanding drum attachment instead. This worked really well and I felt a lot more comfortable that I wasn’t going to take away any more wood than need. With that done, it was time to install the point protectors.

Point protectors, if you did not already know, are hard plastic tips that are glued on to the two body points to help minimize damage. The plastic, as I ordered it, comes as a rectangular block that must be shaped to fit. Mr. Siminoff suggests shaping them first, and then gluing them on, but I decided to do it the other way around - glue first, shape in place. Here is how they looked before, during, and after shaping.

For the last couple of days have been focused on cutting out and installing the inlay work on the peghead and then preparing for the installation of the binding around the body. Because this build has taken so much time and I have come to the conclusion the value is minimal, like the ivy carving on the scroll, I have now decided not to do the ivy inlay on the fretboard. Instead, I will simply put my name on the peghead.

From what I have read, the way to go about installing inlays is to cut out the inlay material first (Mother of Pearl, or MOP), use it to trace the outline onto the wood, route out the pattern and, finally, glue it in place. So to start, I printed out a full-scale copy of my pattern and glued it directly to the MOP. Once the glue was dry it was time to start cutting.

It seems that most of the information I could freely find on the web indicates that most people use hand-held coping saws to cut out their MOP inlays, so that is what I figured I would do. To begin, though, I needed a working platform on which I could rest the part while cutting but one that would allow as much motion as possible. For this, I took a scrap piece of 3/4” plywood, cut out a slot with a hole in the center and a tongue that I could clamp in my vice. Here is what it looks like.

I have no idea what those other people use for a saw blade for cutting this stuff, but the saw blade I tried (finest I have) would hardly make a dent in it and the teeth would catch on the material every stroke. I abandoned the coping saw and moved to a cutting wheel on my Dremel. Much better (and quicker).

Now before anyone can jump on this, let me point out that I already knew that breathing MOP dust is bad for ones health so I was sure to wear a good dust mask while cutting. I also rigged up my shop-vac to suck away as much of the dust as possible.

Once I had cut away as much as I could reach with my cutting wheel, I still had some pretty major areas (and some really small, remote ones) that I couldn’t reach with anything I had on hand. I ended up making a run to the hardware store to purchase both a very fine cutting bit for the MOP and a small router bit for later when it came time to route the mating shape in the peghead. Both bits are for the Dremel.

Here I am using the fine cutting bit - also quite time consuming but well worth it.

And here I am cleaning up the finished shape with my jeweler’s files.

Once I was satisfied that the shape was ready, I located my desired position on the peghead, clamped a bottom guide in place (the blade from a small hand-plane, in this case) and traced the shape with a mechanical pencil.

Using the jig I made for cutting my dovetail as a support for the peghead, I clamped the neck to the jig and the jig in the vice in preparation for routing. I attached my Stew-Mac routing base and new bit to my Dremel, I carefully routed out as much of the shape as I could.

Even though the routing took out the vast majority of wood, there was still a fair amount it couldn’t reach. For this I reverted once again to my carving tools and jeweler’s files.

Of course as I carved and filed I would regularly check my fit against the MOP shape. What I found was that regardless of how careful I tried to be, working with the ebony wood made it really difficult to find the high spots and occasional point I had not yet notched. As a result, the cut-out ended up being quite tight in some places and much too wide in others. Here is how it looked before I glued it in.

One of the techniques that Mr. Siminoff shares in his book is that the gluing in process and gap filling process are one-in-the-same. What you do is to mix fine ebony wood dust with white glue (Titebond, in my case) until you have a very dark, almost black, mixture.

Then, using a small trowel, fill the cut-out with the glue mix and gently press the MOP into the cutout until it is fully inserted. Leave the extra glue which will shrink and suck in to where it is needed.

Once everything is dry, scrape and sand smooth.

I ended up having to add extra glue mix to fill in some gaps where I had not left enough extra the first time. Overall, though, I am quite pleased with the way it turned out.

Finally, then, I got started routing and carving the body for the binding. For this I used a router bit and binding router guide, both from Stew-Mac.

I read that this is a very delicate operation and that it was really easy to mess up, so I took extra precaution and I am glad I did. You really need to pay attention to your wood grain, router bit speed, and feed direction when doing this operation. I found that the most important thing was the feed direction. As long as I made sure to feed opposite the direction of the bit (so that I was trying to run over my chips), the tool never tried to get away from me. On the couple of times I tried it the other way, it jumped and pulled away (fortunately without causing any irreparable damage). As with the routing the peghead, there were, naturally, places I couldn’t reach with the router bit. For these, I am having to cut out by hand. That’s where I am right now.